Apparatus for cooling molds



mm; 535x Qu Sept. 5, 1967 c. c. cowGlLL APPARATUS FOR COOLING Moms FiledJune 17, 1965 COL/N C. COWG/LL By MM nited States latent fifice3,339,624 Patented Sept. 5, 1967 3,339,624 APPARATUS FOR COOLING MOLDSColin C. Cowgill, Gary, Ind., assignor to United States SteelCorporation, a corporation of New Jersey Filed June 17, 1965, Ser. No.464,790 4 Claims. (Cl. 164-154) This invention relates to a method andapparatus for cooling hot molds. More particularly, the inventionrelates to a method and apparatus for cooling hot molds with minimumdamage to the molds themselves and to provide molds in a condition to bequickly re-used. Still more particularly, the invention is useful inautomatically cooling hot molds which have been used in casting steelingots.

Prior to the present invention, hot molds were cooled by manuallyactivated cooling systems, usually comprising a number of water sprayspositioned to supply water to the mold surface. Since such systemsrequired manual operation, they were not well controlled. The moldtemperature at the start of cooling was generally unknown, and as aresult, cooling of the molds often began either When the molds were toohot, causing serious damage to the molds, or too cold, causing waste oftime and facilities. More importantly, poor cooling of the molds resultsin unsatisfactory ingot quality because the molds were frequently cooledto too low a temperature for casting. In addition, a safety hazard ispresented when water remains in the mold at pouring time due tovunnecessarily long cooling cycles or because the molds are cooled downtoo far to vaporize residual water. As a result, pouring hot metal intocold or wet molds causes poor ingot surface quality due to excessivespitting and splashing during metal pouring, and often uncontrollablede-oxidation practices, particularly on mechanically capped andsemikilled steels. Thus, manual systems have not proven satisfactorybecause of the lack of control.

The present invention provides an improve automatic system for coolinghot molds which is easily used and simply constructed. According to theinvention, a system is provided for cooling hot molds which comprises aninfrared sensing device adapted to sense radiant energy emitted from aplurality of hot molds and a cooling system for spraying liquid coolanton the hot molds in response to the radiant energy level sensed by theinfrared sensing device.

An apparatus or system according to the invention is described in theaccompanying schematic drawing which shows a plurality of hot ingotmolds which are transported in ingot buggies 12 into the ingot coolingarea on track 14. An infrared sensing device 20 is positioned to senseand measure radiant energy emitted from a plurality of ingot molds andtransforms the radiant energy sensed into an electrical signal which istransmitted to an amplifier 30. The amplifier demodulates and filtersthe signal and amplifies it to correct amplitudes to provide a suitablevoltage to temperature recorder and controller 40. Controller 40activates the cooling system by energizing a spray timer 50 and a sprayrelay 60. The spray relay 60 operates a spray solenoid 70 that controlsmain valve 72 which supplies coolant from a cooling source through asuitable fluid line 80 to a header 82 and through spray lines 84 toindividual sprays 86.

It has been determined that in cooling iron molds which have been usedin casting steel ingots, the coolant, e.g. water, should not be appliedto the hot molds until the molds are below about 1100 F. or else moldlife is significantly shortened. The full explanation is not entirelyclear; however, it is believed that cooling from much above about 1100F. alters the metallurgical structure of the molds sufiiciently toimpair the usefulness of the mold by reducing its potential life. Forthis reason, in the preferred embodiment of the invention, coolant isnot applied to the molds until the mold temperature is indicated to bebelow about l100 F.

Similarly, it has been found that for optimum casting practice the moldssupplied therefor should not be cooled to below about 550 F. If themolds are cooled much below this temperature, the tendency for residualwater to remain in the molds and interfere with metal casting increasesconsiderably. Moreover, as discussed above, unnecessary cooling ties upmold cooling equipment thereby wasting time and mold cooling facilities.

It is particularly desirable to cool the hot molds in steps rather thanto continuously cool to the desired low temperature. Intermittentcoolant permits the mold temperature to equalize and minimizes thedevelopment of thermal stresses in the molds which shorten mold life byincreasing the incidence of mold damage. To accomplish intermittentcooling, the system is adjusted so that while the cooling system isactivated, a cooling cycle is used which includes spray-on and spray-offperiods in a regular sequence until the mold temperature, as indicatedby the infrared detector, is below about 550 F. which is the temperaturefound to be the desired minimum to which iron molds should be cooled foroptimum steel casting practice.

The arrangement described in the drawing illustrates how commerciallyavailable items can be combined into a new automatic cooling systemwhich provides the aforementioned advantages. Although many temperatureindicators are available, it has been found that a narrow band infraredradiant energy receiver is essential in the system for the necessaryaccuracy over the temperature range encountered and in the environmentinvolved. The infrared receiver used must be capable of measuringradiant energy with wave lengths of from 1 to 7 microns, preferably 2.0to 2.6 microns, within the target area of the detector. The infraredsensing device is aimed so that its target area includes a plurality ofmolds and the reading given by the device will more acurately reflectthe temperature of the group of molds involved rather than the merelylocal temperature of a small area of mold surface. The objective lensare removed from the infrared device in order to increase the fieldarea. For optimum use, the infrared sensing device is aimed so thecenterline of the sensing field strikes the line of molds at an angle off;l5 (i75 from the perpendicular). This orientation provides a muchlarger target area than when placed at a angle, but does not change thetotal radiant energy detected. The amount of flux density (radiantpower) detected remains the same, for any given temperature, regardlessof the angle of incidence becausee the instrument sees a spot ratherthan a point, and an increase in area resolved compensates for adecrease in radiant energy (which varies as the cosine of the anglebetween the normal and the particular direction-by Lamberts Law). At anangle of 15 a missing mold in the line will not significantly affect thetotal radiant energy from the target, since the end wall of the nextmold will find the void in the target. The target area is large enoughto initiate a response which is proportional to the average moldtemperature and it provides dependable operation. Average moldtemperature may be assumed to be represented by a point at the center ofthe surface of the mold sidewall which is 24 inches up from the bottomof the mold, and temperatures measured at this point can be used as acontrol check on temperatures obtained by the infrared units.Compensating adjustments in the output of the infrared device can bemade via the emittance control on the amplifier. The sensing head maybest be aimed by temporary installation of the standard objective lensand sighting through the telescopic optical system to locate the centerof the target. A locking type swivel base may be provided to facilitateaiming the sensing device.

In operation, the infrared detector 20 indicates the mold temperature byautomatically sensing the radiant energy emitted from the molds andtranslates the radiant energy sensed into a proportional electricaloutput. The

signal voltage from the infrared sensing unit is transmitted to anamplifier 30 Where the signal is demodulated, filtered and reduced tocorrect amplitudes to drive an amplifier meter and to provide a suitablevoltage input to external temperature recorder and controller 40. Asuitable sensing device for use according to the invention is an IrconInfrared Thermometer, Model 300T-2 (which includes both a radiationsensing-head 20 and amplifier 30) manufactured by Ircon, Inc., Chicago,Illinois. A suitable recorder-controller is Minneapolis-Honeywellcircular chart electronic recorder Model No. lSZX-l S-RA-Q3-II-W5-11-A4. Within the recorder are a normallyopen low temperaturecontact 42 and a normally-closed high temperature contact 44. The lowtemperature contact 42 closes at approximately 550 F. and thenormallyclosed high temperature contact 44 opens at approximately ll F.These contacts automatically energize a repeat cycle spray timer 50whenever the mold temperature corresponding to the radiant energy asmeasured by the sensing device 20 is between about 550 F. and 1100 F. Asuitable repeat cycle timer is the Flexopulse Repeat Cycle Timer No.HG84A6, manufactured by Eagle Signal Co., anddescribed in companybulletin No. 320.

The switching action of the timer S0 is used to energize and de-energizespray relay 60 which, in turn, energizes and de-energizes spray solenoid70 which controls a double acting main water valve 72. The timer runscontinuously, when energized, until power is interrupted by excursionsbeyond the hi-low limits of the recorder-controller. The timer containsan indicator which oscillates continuously between the settings of twoadjustable stops, and trips a single-pole double-throw switch atmidpoint, thereby controlling on and off periods of the cooling cycle.The adjustable stops can be set to provide on or off period of 5 secondsthrough 20 minutes. The presently preferred conditions include periodsof 5 minutes on and 3 minutes off The timers double-throw switchcontains contact points 1, 2 and 3 as shown in the drawing. The 3-2contact in the timer energizes the spray relay 60 which activates thespray solenoid 70 and valve 72. After the timer completes its spray-oncycle, the 3-2 contact opens thereby de-energizing the spray relay andshutting off spray solenoid 70 (closing valve 72). The 2-1 contactcloses as the 3-2 contact opens and the timer continues through thespray-off period, then repeats the spray-on cycle. When de-energized bythe recorder controller, the timer always stops at the end of an onperiod with the 2-1 contacts closed as a result of a normally-opencontact 62 in the spray relay 60 which seals-in the circuit during thespray-on period of the cycle so that the timer will go through acomplete preset on cycle once energized. The seal-in function of Contact62 serves to overcome erratic operation that might `result from theeffect on the sensing unit of occasional excesses of water and steam inthe cooling area. When the temperature of the molds is brought below 550F., the timer is de-energized by the recorder-controller contact 42 andthe 2-1 contacts will remain closed at the end of vthe on period.

As can be seen, the timer always starts at the beginning of an ofiperiod which results in a 3 minute (or other pre-set time) delay oninitial activation. This delay allows time for personnel to leave thearea before spraying starts after molds are brought in for cooling. Thedelay function could also be performed by a time delay relay, but such arelay is unnecessary if the off period of the timer is utilized for thedelay. A normally-closed contact in the spray relay 60 opens during thespraying period to de-energize the recorder-controller 40 balance motor,so as to avoid erratic recording that may be caused by the sprayingwater. During this-time, the recorder chart will indicate a straightline at the interrupted temperature. The switching action of the spraytimer 50 enables intermittent spraying during cooling of the molds tothe desired temperature. As discussed above, intermittent cooling isdesirable to minimize thermal stresses within the molds caused bydrastic temperature reduction and the time intervals between sprayingperiods allow temperature differences Within the `mold Walls toequalize.

The spray timer cycles the coolant spray on and off until the moldtemperature drops below about 550% F., at which point low temperatureContact 42 opens and deenergizes the spray timer 50. At about this point(525- 550 F.) a low temperature range, normally open contact 46 in therecorder-controller closes and energizes a low temperaturerange-switching relay in the amplifier unit 30 to permit low temperaturemeasuring and recording. A suitable spray relay is magnetic relay No.SSRG made by Clark Controller Co. and described in Bul. No. 7305- PMS. Asuitable spray solenoid is a 4-Way solenoid valve ASCO No. 83441 made bythe Automatic Switch Co. A suitable double-acting main water valve 72 isa 6-inch Dezurik Hydraulic Cylinder Operated Eccentric Valve, FIG. 128Fmade by Dezurik Corp., Sartell, Minnesota.

When molds are placed in the cooling station, the temperature ismeasured by the infrared sensing unit 20 which transmits a signal toamplifier 30. The amplifier regulates and amplifies the signal toprovide an output to recorder 40 which is proportional to moldtemperature. If the ternperature is within the prescribed limits, e.g.550 F. to 1l00 F., as determined by the hi-low temperature contactsettings 44 and 42 on the recorder-controller 40, the repeat cycle timer50 is activated. The timer energizes (and de-energizes) the spray relay60 in accord with preset time intervals and will continue to operate aslong as it is energized by the recorder-controller, thereby providingthe desired water-on (spray-on) and water-off (spray-olf) cycles. Thespray relay controls the opening and closing of the main water valve byactivation of the corresponding pilot valve solenoid 70. The sensingunit measures temperature continuously, Whether the station is occupiedor not, with the exception that the signal from it is blocked out duringthe water-on periods to avoid possible error introduced by the heavyblanket of water and steam.

Modifications may easily be made to increase or decrease the amount ofcontrol or read-out desired. Examples are (l) two-point controllerrather than recordercontroller if recordings are not needed, (2)proportionf ing controller for more sensitive programing of sprayaction, (3) standby manual controls for experimental use or to insureoperation in event of failure of automatic system, (4) thermostaticcontrol of temperature of sensor head and/ or amplifier environmentusing water or air for cooling and electricity for heating, ,(5)automatic drain valve to allow above ground piping to drain at end ofcooling sequence during cold weather operation, (6) single-rangerecorder-controller rather than dual range if temperatures below 500 F.are not needed, or if auditing of time that molds are placed in orremoved from the cooling station is -not desired (7) multipleinstallation of sensing units (8) multiple installation of controlsystem for independent zone or area control, (9) scanning equipment formounting sensing head, (10) closed-circuit TV, mechanical, magnetic, orelectronic limit switches, or other sensing devices for positioningbuggies carrying molds in the cooling station.

It is apparent from the above that various changes and modifications maybe made without departing from 'the invention. Accordingly, theinvention should be limited only by the appended claims.

I claim: v

1. An accelerated cooling apparatus suitable for cooling hot molds fromwhich ingots have been removed comprising a narrow band infrared sensingmeans for sensing radiant energy emission in the wave length range of 1to 7 microns from a plurality of hot molds and to give an indication ofthe temperature relative thereto, a cooling system for spraying liquidcoolant on said hot molds responsive lto said sensing means such thatbelow a maximum sensed radiant energy level and correspondingtemperature range the coolant system is activated and below a minimumsensed radiant energy level and corresponding temperature range thecoolant system is deactivated.

2. An apparatus in accordance with claim 1 for cooling hot iron molds,having means responsive Ito said sensing means to activate anddeactivate said mold cooling system when the temperature correspondingto the sensed radiant energy emission of said molds is about 1100 F. and500 F. respectively.

3. An apparat-us according to claim 1 wherein said infrared sensingmeans senses and measures radiant energy within wave lengths of from 2.0to 2.6 microns.

4. An apparatus according to claim 1 including a timer connected withthe coolant system to apply coolant to the hot molds intermittentlywhile the coolant system is activated.

References Cited UNITED STATES PATENTS 1,3 3 6,456 4/ 1920 Woodward22-200 1,55 6,642 10/ 1925 Smith 22-177 2,206,930 7/ 1940 `Webster22-57.3 2,570,280 10/1951 RoiTman 169-2 2,746,105 5/ 1956 Ratclit 22-1772,799,781 7/1957 Joyce et a1 169-2 3,122,800 3/1964 Naifziger 22--79FOREIGN PATENTS 212,258 11/ 1924 Great Britain.

I. SPENCER OVERHOLSER, Primary Examiner. V. K. RISING, AssistantExaminer.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,339,624 September 5 1967 Colin C. Cowgill It is hereby certified that errorappears in the above numbered patent requiring correction and that thesaid Letters Patent should read as corrected below.

Column 1, line 37, for "improve" read improved column Z, line 50 for"becausee" read because line 57 for "find" read fill column 4, line 10,for "550% F." read 550 F. column 6, line 6, for "1,336,456" read1,336,459

Signed and sealed this 27th day of August 1968.

SEAL) Kttest:

,rf Edward M. Fletcher, Jr. EDWARD J. BRENNER testing OfficerCommissioner of Patents

1. AN ACCELERATED COOLING APPARATUS SUITABLE FOR COOLING HOT MOLDS FROMWHICH INGOTS HAVE BEEN REMOVED COMPRISING A NARROW BAND INFRARED SENSINGMEANS FOR SENSING RADIANT ENERGY EMISSION IN THE WAVE LENGTH RANGE OF 1TO 7 MICRONS FROM A PLURALITY OF HOT MOLDS AND TO GIVE AN INDICATION OFTHE TEMPERATURE RELATIVE THERETO, A COOLING SYSTEM FOR SPRAYING LIQUIDCOOLANT ON SAID HOT MOLDS RESPONSIVE TO SAID SENSING MEANS SUCH THATBELOW A MAXIMUM SENSED RADIANT ENERGY LEVEL AND CORRESPONDINGTEMPERATURE RANGE THE COOLANT SYSTEM IS ACTIVATED AND BELOW A MINIMUMSENSED RADIANT ENERGY LEVEL AND CORRESPONDING TEMPERATURE RANGE THECOOLANT SYSTEM IS DEACTIVATED.